EDDY CURRENT BRAKE! What’s interesting is that when charges swirls as eddy currents, they interact with the external Bfield to produce a force that fights both their entrance and exit from the field. In other words, they act like a brake.! Aluminum is not magnetizable (it is a metal so you can get current to flow, but it doesn’t have magnetic domains like iron). So consider an aluminum disk that is made to rotate, and that has a portion of its surface continuously passing through a magnetic field directed into the page (see sketch).! 1.! At a given instant, the electrons in the area of the metal that is moving into the external B-field will experience an induced eddy currents! EMF which will make them swirl. The same will happen as the metal leaves the magnetic field. This swirling of charge is called “eddy currents.”! (Note that in the set-up shown, Lenz’s Law suggests that the induced current (the charge swirl) in the entrance (upper) section rotates counterclockwise whereas the induced current in the exit (lower) section rotates clockwise.)! 2.! magnetic force! magnetic force! 3.!